1. Field of the Invention
The present invention relates generally to air entangled yarns and, in particular, to an apparatus and technique for combining natural and manmade spun yarns with continuous filament yarns and the products produced thereby.
2. Description of the Prior Art
It is well known that spun yarns formed from stable fibers may be used to produce fabrics having superior aesthetic properties such as a soft hand and a warmer appearance. However, spun yarns have limited stretchability and articles of apparel made from spun yarn alone must be made to closer tolerances in order to be comfortable to the wearer. This limitation is particularly troublesome in articles of apparel, such as men's hosiery, where it is desirable that only a limited number of sizes be produced in order to keep inventory costs low. Other yarn types are available, such as continuous multifilament stretch nylon, which possess the prerequisite stretchability. However, fabrics produced from these materials have generally not received wide consumer acceptance due to their poor "feel".
One way of producing a fabric which has the feel of spun yarns and the stretchability of continuous filament yarns has been by creating a composite yarn or fabric. A composite includes two or more yarns having complementary characteristics.
One method of producing a composite is plaiting. Plaiting involves knitting two different yarns in such a manner that one yarn becomes the face of the article and the other one the back of the article. Plated knit fabrics are particularly suitable for men's hosiery. A second method for producing a composite yarn is plying. Ply yarn is made by having two or more yarns that have been twisted together. Ply yarns may be equally wrapped about one another or one of the yarns may serve as the core and the other as an outer layer about the core. For example, core-spun sewing thread is made with a core of manmade filament yarn and covered with high quality cotton to give a strong thread with the surface and friction properties of cotton. Both of these processes are slow, high cost processes. For example, plaiting produces a large number of second quality goods due to mis-plaits when the inner yarn (for example, the nylon yarn) delivers unevenly and flips over to top. The resulting sock will be streaked after dying. In addition, ply yarns have a tendency to separate, thereby increasing the likelihood that one loop will be missed by the knitting machine and result in a defect.
On the other hand, yarns consisting of two or more continuous multifilament yarns have been produced by entangling the relative filaments about one another with jets of high velocity fluid. Samples of these yarns and the processes which produced them are shown in U.S. Pat. No. 3,940,917 issued to Strachan and U.S. Pat. No. 3,991,548 issued to Toronyi. However when continuous filament yarns and spun yarns have been combined, unstable or wild loops are formed.
One technique for eliminating these loose loops includes a process of continuously drawing the continuous filaments under controlled temperature conditions, air jet texturizing the drawn yarn, and then subjecting the textured yarn to saturated steam while restraining the yarn from shrinking during the steam treatment. An example of such a process is shown in U.S. Pat. No. 4,567,720 issued to Price. However, the process as taught by Price is directed to removing the unstable or wild loops which have already been formed in the air jet and requires a close control of the process temperatures.
As a result, air entangled continuous multifilament and spun yarns have been used primarily to produce a randomized novelty yarn which exhibit essentially no uniform characteristics. An example of such a process is shown in U.S. Pat. No. 4,212,152 issued to Roman. The Roman reference provides a particularly detailed discussion of the problems and processes for producing such novelty yarns.
It has thus become desirable to develop a process for producing a composite continuous multifilament and spun yarn which prevents the formation of unstable and wild loops which have previously plagued conventional fluid jet entangling apparatuses. The resulting yarn is suitable as a replacement for plied and plaited yarn and may be produced by a much faster process at lower costs, improved efficiency, and quality, thereby reducing the amount of second quality goods.